Most chemotherapeutic drugs affect both tumor and normal cells, are ineffective in a number of patients, and exhibit serious toxicity;hence developing predictive models that identify patients at risk for adverse reactions and/or non-response to chemotherapeutic agents prior to treatment is essential. An objective of this proposal is to take a concerted translational effort to elucidate the underlying cause for the inter-ethnic differences in sensitivity to chemotherapy. In this proposal, we will focus on two classes of cytotoxic agents: platinating agents (cisplatin and carboplatin) and antimetabolites (capecitabine and Ara-C), of which significant inter-ethnic differences in cellular sensitivity have been observed in vitro. Our hypothesis is that there are microRNA (miRNA) expression differences in individuals of African descent compared to individuals of European descent that contribute, at least in part, to the difference in sensitivity to chemotherapy-induced cytotoxicity in these two populations. Our long-term goal is to develop an unbiased genome-wide model to identify germline genetic variants, mRNA or miRNA expression including those in an underserved population, that predict risk for adverse reactions and non-response to chemotherapy. Our hypothesis is that there is a set of germline pharmacogenetic polymorphisms associated with the expression of miRNA that affect chemotherapy-induced cytotoxicity and these polymorphisms exhibit interethnic differences. Our specific aims are 1) To quantify genome-wide miRNA expression in HapMap lymphoblastoid cell lines (LCLs) and to identify SNPs associated with miRNA expression and chemotherapy-induced cytotoxicity;2) To identify mRNA and miRNA expression signatures that significantly correlate with chemotherapy sensitivity and to compare the miRNA expression chemotherapeutic sensitivity signatures in different ethnic populations;3) To replicate our findings in additional LCLs. PUBLIC HEALTH RELEVANCE: This proposal is intended to better understand how genetic variation contributes to individual sensitivity to chemotherapy. The long term goal is to identify patients, using their genetic make up, that are at risk for toxicities associated with chemotherapy with the intent to reduce their chances of an adverse event.